Dear all, To test kwant as a beginner I wanted to solve a CIP GMR system (not CPP). Usual config. is 2 FMs separated by a NM; however because it is CIP, then the leads are partially connected to the 3 layers My system extends from the quantum wire problem adding Pauli matrices and the conservation law sigma_z I added impurities using a random function; however, my output sometimes shows a larger conductance for the antiparallel case (rather than the parallel one). No integration involved, simple conductance calculation using: "smatrix.transmission(1, 0))". From a code perspective, my only concern is on the leads, for instance I have for one ferromagnet: leftlead[(lat(0, j) for j in range(W))] = Jxc * (sigma_x*mx + sigma_y*my + sigma_z*mz ) I do not add impurities on the leads. the 4t term is not taken as i shifted the bandwidth. Is this a good "oversimplified approach? From a kwant perspective, As I said, sometimes the AP case is larger than the P config. Because of this I performed a random distribution average over 10000 loops and my result shows that in 25% of the cases AP is larger than P. Why it is not possible to get a solution to this system with low error? Is it because the quantum wire conductance problem is too simple to give proper results for CIP GMR? Shall I avoid using the conductance and focus instead on current out of equlibrium? Or CIP-GMR has particular constraints that I'm omitting in Kwant. Thanks a lot for a response...